Despite vehement denials from Macaulay Culkin's rep that the former child star is addicted to heroin, the National Enquirer, which first reported on the story, is sticking to its guns — and upping the ante.

"The National Enquirer hopes the cover story on its latest issue...will act as a dramatic and much-needed wake-up call to the 31-year-old actor," Enquirer editors wrote in a statement posted on the tabloid's site. "Our advice to Macaulay is to seek professional help to avoid the same tragic fate of other beloved celebrities, including Whitney Houston who died earlier this year."

Macaulay Culkin nearly overdosed on heroin and has a $6,000-a-month oxycodone habit, the National…
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"Should Macaulay's representatives continue to deny The ENQUIRER's accurate and detailed report," the statement continues, "we are ready to offer him the opportunity to take a blood test administered by an independent medical lab."